According as nanotechnology has been developed, colloidal silica materials comprising nanosized silica particles have been getting widely used. Colloidal silica is generally known to improve the thermal and mechanical properties of materials mixed therewith, and hence is employed as an additive in various resins and dispersion media. However, commercially available colloidal silica is generally in the form of aqueous colloidal solution or powder, and is accordingly poor in dispersibility when added in organic dispersion media or resins. In view of that, in order to solve the problem of dispersibility, it has been desired to provide non-aqueous colloid (which is also referred to as “organosol”).
Heretofore, many attempts have been made to produce non-aqueous colloid. In those attempts, surface of colloidal silica is modified (to be hydrophobic) so as to manufacture organosol materials homogeneously dispersible in organic dispersion media (for example, see, Patent documents 1 to 4).